A common type of sprinkler head, as used in an automatic sprinkler system, is a recessed type in which the sprinkler head is partially mounted within a recess in the ceiling and the lower portion of the sprinkler head is exposed beneath the ceiling.
A recessed sprinkler head normally includes a cup-like member which is spaced outwardly of the sprinkler head and carries a decorative ring that bears against the lower surface of the ceiling to hide the opening in the ceiling within which the sprinkler head is mounted. The cup and decorative ring can be moved relative to the sprinkler head so that after the sprinkler head is connected to the water line, the cup is moved upwardly to bring the decorative ring in contact with the ceiling.
With the conventional recessed sprinkler head, the cup member and decorative ring are normally pre-assembled with the sprinkler head prior to connecting the head to the water line. In some cases, the cup member is carried by a support plate which is threaded onto the upper end of the sprinkler head, while in other cases the support plate is slipped over the upper threaded end of the sprinkler head and supported on the frame.
After connection of the sprinkler head to the water line, testing of the system is required. The primary location of possible leakage is at the threaded connection between the sprinkler head and the water line. With the cup member and support plate pre-assembled with the sprinkler head, it is difficult to see if leakage is occurring at the threaded joint.
Another problem encountered with recessed sprinkler heads, as used in the past, is that very often relative movement occurs between the water piping system and the ceiling due to settling of the building. If the water line moves downward relative to the ceiling, a gap occurs between the decorating ring and the ceiling which can cause an unattractive appearance. On the other hand, if the water line moves upwardly relative to the ceiling, increased stress can be applied to the sprinkler head due to the added weight of the ceiling.
Because of this problem, attempts have been made to provide a floating action for the decorative ring to permit the ring to float in accordance with relative movement between the water line and the ceiling. For example, U.S. Pat. No. 3,389,884 shows a sprinkler head assembly in which a cup-shaped support member is threaded on the upper end of the sprinkler head, and a sleeve, which carries a decorative ring, is connected to the support member through a compression spring. With this construction, the biasing effect of the spring will compensate for relative movement between the water line and the ceiling, enabling the decorative ring to be maintained in intimate contact with the ceiling. However, the sprinkler head construction of the aforementioned patent has a disadvantage in that the support plate, sleeve and decorative ring must be pre-assembled to the sprinkler head before the sprinkler head is connected to the water line. With this pre-assembled construction, special tools are required to thread the sprinkler head to the water line, and because of the presence of the sleeve and support plate, it is difficult to observe if leakage occurs at the threaded joint during testing of the water system.